| 吕功煊.高分子修饰Pt/ZnS-CdS/SiO2催化剂表面官能团调变[J].分子催化,2012,(3):265-275 |
| 高分子修饰Pt/ZnS-CdS/SiO2催化剂表面官能团调变 |
| Studies on photocatalytic hydrogen production relating to the surface functional groups’ modulation of polymer-modified Pt/ZnS-CdS/SiO2 |
| 投稿时间：2012-05-04 修订日期：2012-05-29 |
| DOI： |
| 中文关键词: Pt/ZnS-CdS/SiO2 高分子修饰 表面官能团 光催化 制氢 |
| 英文关键词:Pt/ZnS-CdS/SiO2 polymer-modification surface functional groups Photocatalytic hydrogen generation |
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| 摘要点击次数: 1681 |
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| 中文摘要: |
| 用丙烯酸酯和环氧树脂将亲水性的-OH和芳香性的苯环修饰到Pt/ZnS-CdS/SiO2催化剂表面，在不同气氛下进行热处理后，考察了这些催化剂的可见光催化分解水产氢活性。结果表明，修饰和热处理后催化剂活性有着不同程度的下降。XRD结果表明，空气热处理致使催化剂中CdS由立方晶型向六方晶型转变，ZnS由六方晶型向α-ZnS晶型转变；氢气热处理导致生成六方结构的固溶体Zn0.5Cd0.5S，这种转变与催化剂是否经过修饰无关，催化剂结构仍为ZnS为外层、CdS为内层的核壳形态。HRTEM结果表明表面修饰使催化剂表面Pt平均粒径由18 nm减小为6 nm。紫外可见漫反射（UV-Vis DRS）结果表明，经修饰和热处理后的催化剂在450~800 nm区间的光吸收增加，在空气中500 ℃条件下煅烧后的催化剂的吸收限由480 nm红移至520 nm，而在氢气中于500 ℃条件下煅烧后吸收限则由480 nm蓝移至420 nm。修饰后催化剂的羟基吸收强度增大，出现了苯环的特征吸收峰。红外光谱(IR)结果表明空气热处理导致部分含氧官能团发生了脱离，但羟基吸收峰强度增强；氢气热处理导致C-O和C-O-C的吸收峰峰强度增强，表明催化剂表面发生了碳化。热重和差热分析（TG-DTA）与红外结果均证实了这种变化。产氢活性下降可能归结为表面羟基的减少导致催化剂分散性和光生电荷的分离效率降低；催化剂表面的含氧官能团占据了催化活性位并且降低了颗粒在水溶液中的分散性。 |
| 英文摘要: |
| The hydrophilic -OH group and aromatic benzene ring were modified to the surface of synthetic Pt/ZnS-CdS/SiO2 complex photocatalyst through acrylate resin adhesive and epoxy resin. Then the particles were respectively calcined in atmosphere and hydrogen at different temperature. The photocatalytic hydrogen-producing activity of the resulting photocatalysts was investigated. The results showed that modification and heat treatment made the catalyst’s activity decrease by different degrees. The XRD results showed that the characteristic peaks of ZnS and CdS were not changed after modification, but its crystalline changed from cubic-type CdS and hexagonal-type ZnS into hexagonal-type CdS and α-ZnS after heat treatment in air, while the hexagonal structure solid solution Zn0.5Cd0.5S was formed between cubic-type CdS and hexagonal-type ZnS in hydrogen. The heat treatment of unmodified catalysts in both air and hydrogen led to the same phase transformation. HRTEM results showed that the catalyst’s average diameter reduced from 18 nm to 6 nm after surface modification while the surface structure of a CdS core and ZnS shell was not changed. UV-Vis DRS results showed that the light absorption of the compound semiconductor materials enhanced after modification and heat treatment in the range of 450 to 800 nm. The absorption edge of the catalyst red shifted from 480 nm to 520 nm after heat treatment at 500 ℃in air, while it blue shifted from 480 nm to 420 nm in hydrogen. Despite the interface-modified catalysts’ photoabsorption performance were improved, the hydroxyl absorption was enhanced after modification, and the characteristic absorption of benzene ring appeared. IR results showed that these functional groups had significant difference after heat treatment. Some oxygen containing functional groups desorbed and the hydroxyl absorption was enhanced when underwent heat treatment in air, while the absorption of oxygen containing functions such as C-O and C-O-C were enhanced in hydrogen. These changes were also confirmed by TG-DTA results. The decrease of hydrogen-producing activity may be attributed to the reduction of the reaction system’s dispersion and separation efficiency of photogenerated charges, both of which were caused by the reduce of the surface hydroxyl groups; the oxygen containing functional groups on the catalyst surface occupied the catalytic active sites and reduced the particles’ dispersion in aqueous solution. |
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